define(['exports', './Matrix3-4f4df527', './defaultValue-0a909f67', './Check-666ab1a0', './Math-2dbd6b93'], (function (exports, Matrix3, defaultValue, Check, Math$1) { 'use strict';

  /**
   * The map projection used by Google Maps, Bing Maps, and most of ArcGIS Online, EPSG:3857.  This
   * projection use longitude and latitude expressed with the WGS84 and transforms them to Mercator using
   * the spherical (rather than ellipsoidal) equations.
   *
   * @alias WebMercatorProjection
   * @constructor
   *
   * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid.
   *
   * @see GeographicProjection
   */
  function WebMercatorProjection(ellipsoid) {
    this._ellipsoid = defaultValue.defaultValue(ellipsoid, Matrix3.Ellipsoid.WGS84);
    this._semimajorAxis = this._ellipsoid.maximumRadius;
    this._oneOverSemimajorAxis = 1.0 / this._semimajorAxis;
  }

  Object.defineProperties(WebMercatorProjection.prototype, {
    /**
     * Gets the {@link Ellipsoid}.
     *
     * @memberof WebMercatorProjection.prototype
     *
     * @type {Ellipsoid}
     * @readonly
     */
    ellipsoid: {
      get: function () {
        return this._ellipsoid;
      },
    },
  });

  /**
   * Converts a Mercator angle, in the range -PI to PI, to a geodetic latitude
   * in the range -PI/2 to PI/2.
   *
   * @param {Number} mercatorAngle The angle to convert.
   * @returns {Number} The geodetic latitude in radians.
   */
  WebMercatorProjection.mercatorAngleToGeodeticLatitude = function (
    mercatorAngle
  ) {
    return Math$1.CesiumMath.PI_OVER_TWO - 2.0 * Math.atan(Math.exp(-mercatorAngle));
  };

  /**
   * Converts a geodetic latitude in radians, in the range -PI/2 to PI/2, to a Mercator
   * angle in the range -PI to PI.
   *
   * @param {Number} latitude The geodetic latitude in radians.
   * @returns {Number} The Mercator angle.
   */
  WebMercatorProjection.geodeticLatitudeToMercatorAngle = function (latitude) {
    // Clamp the latitude coordinate to the valid Mercator bounds.
    if (latitude > WebMercatorProjection.MaximumLatitude) {
      latitude = WebMercatorProjection.MaximumLatitude;
    } else if (latitude < -WebMercatorProjection.MaximumLatitude) {
      latitude = -WebMercatorProjection.MaximumLatitude;
    }
    const sinLatitude = Math.sin(latitude);
    return 0.5 * Math.log((1.0 + sinLatitude) / (1.0 - sinLatitude));
  };

  /**
   * The maximum latitude (both North and South) supported by a Web Mercator
   * (EPSG:3857) projection.  Technically, the Mercator projection is defined
   * for any latitude up to (but not including) 90 degrees, but it makes sense
   * to cut it off sooner because it grows exponentially with increasing latitude.
   * The logic behind this particular cutoff value, which is the one used by
   * Google Maps, Bing Maps, and Esri, is that it makes the projection
   * square.  That is, the rectangle is equal in the X and Y directions.
   *
   * The constant value is computed by calling:
   *    WebMercatorProjection.mercatorAngleToGeodeticLatitude(Math.PI)
   *
   * @type {Number}
   */
  WebMercatorProjection.MaximumLatitude = WebMercatorProjection.mercatorAngleToGeodeticLatitude(
    Math.PI
  );

  /**
   * Converts geodetic ellipsoid coordinates, in radians, to the equivalent Web Mercator
   * X, Y, Z coordinates expressed in meters and returned in a {@link Cartesian3}.  The height
   * is copied unmodified to the Z coordinate.
   *
   * @param {Cartographic} cartographic The cartographic coordinates in radians.
   * @param {Cartesian3} [result] The instance to which to copy the result, or undefined if a
   *        new instance should be created.
   * @returns {Cartesian3} The equivalent web mercator X, Y, Z coordinates, in meters.
   */
  WebMercatorProjection.prototype.project = function (cartographic, result) {
    const semimajorAxis = this._semimajorAxis;
    const x = cartographic.longitude * semimajorAxis;
    const y =
      WebMercatorProjection.geodeticLatitudeToMercatorAngle(
        cartographic.latitude
      ) * semimajorAxis;
    const z = cartographic.height;

    if (!defaultValue.defined(result)) {
      return new Matrix3.Cartesian3(x, y, z);
    }

    result.x = x;
    result.y = y;
    result.z = z;
    return result;
  };

  /**
   * Converts Web Mercator X, Y coordinates, expressed in meters, to a {@link Cartographic}
   * containing geodetic ellipsoid coordinates.  The Z coordinate is copied unmodified to the
   * height.
   *
   * @param {Cartesian3} cartesian The web mercator Cartesian position to unrproject with height (z) in meters.
   * @param {Cartographic} [result] The instance to which to copy the result, or undefined if a
   *        new instance should be created.
   * @returns {Cartographic} The equivalent cartographic coordinates.
   */
  WebMercatorProjection.prototype.unproject = function (cartesian, result) {
    //>>includeStart('debug', pragmas.debug);
    if (!defaultValue.defined(cartesian)) {
      throw new Check.DeveloperError("cartesian is required");
    }
    //>>includeEnd('debug');

    const oneOverEarthSemimajorAxis = this._oneOverSemimajorAxis;
    const longitude = cartesian.x * oneOverEarthSemimajorAxis;
    const latitude = WebMercatorProjection.mercatorAngleToGeodeticLatitude(
      cartesian.y * oneOverEarthSemimajorAxis
    );
    const height = cartesian.z;

    if (!defaultValue.defined(result)) {
      return new Matrix3.Cartographic(longitude, latitude, height);
    }

    result.longitude = longitude;
    result.latitude = latitude;
    result.height = height;
    return result;
  };

  exports.WebMercatorProjection = WebMercatorProjection;

}));
